Smiling is probably one of the most powerful “language” which can uplift and change the mood of almost any situation. French photographer Réhahn tries to explore the culture of smiles around the world through a portrait project he calls “The Hidden Smile“. The project began when Réhahn was searching for a cover for his book titled Vietnam, Mosaic of Contrasts. He found Vietnamese, especially females, instinctually cover their faces as they giggle, speak or smile. The reason behind of the covering smile can be dated back hundreds of years when a common belief was that only evil spirits, savages, and wild animals possessed long, white teeth. Although the tradition and cultures have changed over time this practise has become outdated, however it is still a natural reaction to cover up ones teeth upon meeting new people or taking a photo in certain areas. Even the mouth has been covered, peoples’ smiles still radiated – that is where the hidden smile comes from.